Try Anna's Archive, matey. Bunder's papers are hard to find. It's been a while, but I think that "illiative" approach is precisely what Bunder tried to articul

Try Anna's Archive, matey. Bunder's papers are hard to find. It's been a while, but I think that "illiative" approach is precisely what Bunder tried to articulate. I recall one paper where he proved you could do set their with Combinator Logic and an "element of" operator. I think.